Generally, a vacuum cleaner is an apparatus to suck dust-included air by using a vacuum pressure generated from a suction motor provided in a cleaner body, and then to filter foreign materials from the inside of the cleaner body.
Such a vacuum cleaner is classified into a passive vacuum cleaner manipulated by a user, and a robot cleaner which autonomously performs a cleaning operation without a user's manipulation.
The robot cleaner is an apparatus capable of autonomously performing a cleaning operation while running on a desired cleaning region, according to an input program, by using a charged battery as a driving source.
Generally, the robot cleaner determines a cleaning region by running on a wall or an outer periphery of a region surrounded by obstacles, through a sensor, and then searches for a cleaning path to clean the determined cleaning region. Then, the robot cleaner calculates a running distance and a current position, based on a signal detected from a sensor which detects an rpm and a rotation angle of wheels, and runs on a preset cleaning path.
The robot cleaner is provided with a running unit to move or rotate a cleaner body back and forth and right and left. Generally, the running unit includes main wheels disposed at right and left sides of the cleaner body, and supplementary wheels for assisting a movement of the cleaner body together with the main wheels.
A driving capability of the robot cleaner is mainly determined by the main wheels. The main wheels may have a smaller diameter with respect to a height of an obstacle (e.g., a stairstep-shaped region such as a threshold), or may have a degraded ground contact force according to a material/hardness. This may cause the robot cleaner to have a lowered running performance including a sliding performance on an obstacle.